Inspiration is where you find it, or in this case, where you read it, as I did in the "Flowers & Flames" section of this very magazine. Commonly known as letters-to-the-editor, this section gives readers their own bully pulpit for agreeing with us (flowers) or taking us to task (flames). Freedom of speech being as sacred a concept as freedom of the press around here, I suspect our editors shuffle though a healthy dose of flames as well as flowers each month.

And yes, I’ve garnered my share of both over the years. The flames especially please me. If you’re a writer who doesn’t spark a few hot flames now and then, you’re not saying much.

The reader-writer of the "flame" in question, however, took issue not with me this time, but our own Dave Spetnagel, Running Times’ shoe reviewer extraordinaire. Now, Dave and I are old friends. Not that I would take a bullet for him, but I’d cover his lunch tab anytime and not worry about it. I like his writing, too.

He had written a piece on the evils of so-called discount running shoes sold in big stores that smell like popcorn. (Imagery mine; he referred to them as Target and Kohl’s.) His point was that you pretty much get what you pay for. In a world where the average price for good shoes in a running store is pushing $100, a forty-dollar running shoe is usually nothing more than a pretty good forty-dollar running shoe. Nothing inflammatory there.

The reader got his back up like a cornered junkyard dog, however, when Dave implied that such a moderately priced shoe may be appropriate only for occasional jogging. Yep, you guessed it, the guy had run seven marathons in a pair of forty-dollar running shoes. Not only that, he ran those seven marathons in eight weeks.

I suspect on his week off, he went grocery shopping. Most of us wouldn’t dream of doing so many miles in so short a period, much less be willing to attempt it, but all of us would agree that the effort would burn a bundle of calories. To fuel seven marathons, his pasta sauce tab alone at Safeway had to be way over forty bucks. Good thing his body can get by with cheap shoes.

Which is the point. Only the exceptionally gifted running body should attempt such a feat with its feet, regardless of how much is spent on shoes. Gifted running bodies typically need less support and protection from running shoes. That’s why I wasn’t surprised to read that this reader was planning his eighth marathon in that same pair of shoes. No doubt he’ll do just fine.

So why shouldn’t everyone run in these very affordable "McSneakers?" Well, for the same reason we don’t all eat Egg McMuffins for breakfast and Big Macs for lunch. It just doesn’t work for all of us. Besides, why wait in line at a drive-through for a bag of mostly saturated fat when you’re willing and able to pay for a better balanced sit-down meal prepared by a chef?

And it’s not just the experience of visiting a small, friendly running store operated by a charming Shoe Guy instead of a giant discount store operated by a team of associates in red vests that we’re talking about. The hundred-dollar shoes really are better shoes. You really do get what you pay for, that is, if you don’t mind paying for it.

Simply put, more expensive running shoes are made of better materials, and they’re built by more highly skilled workers in better-managed factories. Shoe brand name has nothing to do with it. All brands build great shoes in the best factories, but they also contract with, ahem, the fast-food equivalent of factories to build cheap shoes.

All right, so you’re OK with an upper that maybe doesn’t fit very comfortably, doesn’t breathe very well, or doesn’t pamper your feet at all, fine. Maybe you don’t need fibers that reflect heat and UV rays, extra eyelets and loops to ensure a good fit, or welded overlays that support without adding weight. Good for you. Buy the forty-dollar shoes.

What you don’t see, however, can come back to bite you. The foam midsole used in most running shoes, regardless of price tag, is the heart of the shoe. It is here that the shoe cushions and stabilizes your foot, step after step, mile after mile.

And foam is not just foam. The materials that go into it, the manufacturing techniques that create it, and the quality control standards employed all line up with the price of the shoes. For a hundred bucks, you get foam that is consistent in quality and density, and constructed in a fashion that will make it perform consistently for hundreds of miles.

For forty bucks, you might win the foam lottery and get an adequate midsole, or you might get a mixture of a lower grade foam mixed with factory floor sweepings that are occasionally dumped into the vat. No kidding.

You can indeed save money when you eat fast food, buy a used car, or snatch up a forty-dollar running shoe. And there’s nothing wrong with any of that, forty-dollar running shoe included, if it works for you, and that’s what you’re willing to spend.

Just don’t track down one of those red-vested sales associates when those bargain shoes get into an argument with your knees. If you can actually find one, you’ll likely get that universal answer that must be part of big-box retail associate training: "I usually work in small appliances."